BACKGROUND&AIM: To study the effect of photodynamic therapy(PDT)on ultrastructure of esophageal carcinoma cells. MATERIAL AND METHODS: After action of photosensitizer for6,12,and24hours respectively,cultured esophageal carcinoma cells were irradiated with Ultraviolet B(UVB)for half an hour.The ultrastructure of esophageal carcinoma cells in experimental groups and control groups were observed under transmission electron microscope. RESULTS: PDT resulted in condensation of mitochondria,reduction of rough end...